physics help!! Can anyone figure any of these out? Thanks!?

Question

1) A 1550 kg car moves down a level highway under the actions of two forces: a 1070 N forward force exerted on the drive wheels by the road and a 1020 N resistive force. Use the work-energy theorem to find the speed of the car after it has moved a distance of 16 m, assuming that it starts from rest.
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2) A skier of mass 63 kg is pulled up a slope by a motor-driven cable.
(a) How much work is required to pull him 85 m up a 30° slope (assumed frictionless) at a constant speed of 2.4 m/s?
___ J
(b) What power must a motor have to perform this task?
___ hp

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3) A block of mass 12.0 kg slides from rest down a frictionless 35.0° incline and is stopped by a strong spring with k = 3.00 104 N/m. The block slides 3.00 m from the point of release to the point where it comes to rest against the spring. When the block comes to rest, how far has the spring been compressed?
___ m

Answer 1

1) The net force is responsible for motion or net energy is being converted from potential to kinetic

Energy supplied -energy used for for braking = kinetic energy

F1 d - F2 d= .5mv^2
v=sqrt(2 (f1-f2)d/m)
v=sqrt(2(1070 - 1020) 16/1550)
v=1.01 m/s

2) W=dF
W=hmg (the work is equivalent to lifting the skier up, no work is done in the horizontal plane)
W= 85 x 9.81 x 65 =52,532 Joules

3) Power = energy/time or = Fv

F=mg cos(angle of the incline)
P=mg cos(angle of the incline) v
P=63 x 9.81x cos(30) 2.4=1285 Watts

I hope it was useful.